US made Marantz use of silver mica caps

[MBuras]

The subject comes from my recent acquisition of a Marantz 1120 which has build quality unlike the 22xx receivers and amps of the mid to late 70's. Despite restoring many dozens of the aforementioned units this will be my first experience with the US made units which feature large use of axial e-caps and silver mica galore.

I know this subject is likely to ignite a firestorm from Team: Keep It Original vs Team: Replacement but I'm not really looking for that. I am interested in any information on why Marantz US used so many of the silver mica caps in the older units (all over the phono and tone sections) and if that reasoning still holds up in todays world with such advanced capacitor technology. I know from recent research that silver mica caps are crazy expensive today. Was that always the case? And does/did expense equal high quality? Is there any known degradation of the silver mica construction?

Any information more experience members can provide on this subject would be greatly appreciated as I expand my knowledge of these beautiful vintage pieces.

Thanks,
Mike

 

[Leestereo]

Silver mica capacitors are very high quality types and AFAIK, have always been expensive. They are typically very long lived and rarely need to be replaced; that said, there is some evidence that subjecting them to DC voltage over a long period (i.e., decades) will degrade them. If they do need to be replaced, C0G types can be used.

 

[MBuras]

Thanks for the info Ben. I was kinda hoping you’d know something about these caps. They all look in good physical condition so I’ll be keeping them during the resto unless I find one way out of spec.